Abstract
Background Certain population subgroups, including people with lower socioeconomic status, racial and/or ethnic minorities, and individuals with lower literacy skills, face greater health challenges and participate significantly less in health intervention research. This leads to non-generalizable findings and interventions that fail to meet their needs. Despite the recognition of barriers, such as mistrust, limited access, and communication challenges in previous research, strategies to overcome these barriers are still insufficiently implemented. This review of reviews aimed to synthesize existing intervention strategies for improving the recruitment and retention of underserved populations in health intervention research across health domains and assess evidence on their effectiveness. Methods A systematic review of existing reviews was conducted in three databases (i.e., PubMed, PsycINFO, and Scopus) to identify, summarize, and synthesize strategies used to reach, involve, and maintain underserved populations in health intervention research. The following inclusion criteria were applied: (systematic) reviews and/ or meta-analyses published in English between January 2013 and January 2026, with a focus on strategies for the inclusion of underserved populations in health intervention research. Results A total of 18 reviews published between 2014 and 2026 met all inclusion criteria, the majority (N = 11) being systematic reviews. The findings revealed considerable overlap across reviews, underscoring that certain strategies are frequently used. A comprehensive summary of these strategies is provided, categorized based on their primary goal: (1) encouragement strategies to improve outreach to underserved populations, (2) facilitation strategies to improve their participation, and 3) retention strategies to maintain their participation. However, retention was rarely addressed as a primary focus in the included reviews. Conclusions After integrating evidence across reviews from diverse health domains and underserved populations, the findings of this review of reviews highlight the importance of a multifaceted recruitment strategy that incorporates and/or combines approaches and serve goals throughout the health intervention research process. *Correspondence: Jeroen Pronk jeroen.pronk@tno.nl Full list of author information is available at the end of the article Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’